Paper drive mechanism in a high speed printer



y 1965 F. G. PENSAVECCHIA 3,185,078

PAPER DRIVE MECHANISM IN A HIGH SPEED PRINTER Filed Sept. 21, 1961 2Sheets-Sheet l Farmdt Control INVENTOR Frank 6. Pensavecchl'a BY Wfir PATTORNEY PAPER DRIVE MECHANISM IN A HIGH SPEED PRINTER Filed Sept. 21,1961 May 25, 1965 F. G. PENSAVECCHIA 2 Sheets-Sheet 2 mkm INVENTOR Frank6. Pensavecch/a United States Patent C) 3,185,078 PAPER DRIVE MECHANESMN A HIGH SEEED PEWTER Frank G. Pensavecchia, Urchard Lake, Mich,assigncr, lay mesne assignments, to Control Data Corporation,

Minneapolis, Minn, a corporation of Minnesota Filed Sept. 21, i961, Ser.No. 139,679 11 Claims. (Cl. 10193) This invention relates to printersfor use with electronic computers, and particularly to a novelelectro-mechanical, so-called, on-the-fiy type printer. Morespecifically, this invention relates to the means employed in theprinter for advancing the paper or other record strip on which thecharacters are printed.

A complete description of a printer with which my invention can be used,is found in application Serial No. 138,157 entitled High Speed Printer.The pinter includes a continuously rotated print drum having charactersspaced radially around the drum in horizontal rows of identicalcharacters to be printed. Printing takes place by causing hammers todrive the paper into the characters on the drum.

The printer disclosed therein may be used in conjunction with acomputer-buffer combination as a medium and/ or high speed dataprocessing system. For example, the particular embodiment of the printerdisclosed therein is capable of printing 120 character lines at a rateof 150 lines per minute, and under special circumstances at a rate of600 lines per minute for all numeric characters. The computer derivesthe necessary information and places it on its output terminals in sucha way that it is fed into the printer one line at a time. After thecomputer has completed the derivation of one line of information, itthen derives the vertical format or number of lines which the computerdesires to skip on a printed sheet before it prints the next line. Thisinformation is also fed out onto the computer output lines and used bythe printer.

My invention is primarily concerned with the paper advance mechanism,various details thereof, and with the relationship of the paper advancemechanism and a for mat controlled device which is not only slaved tothe paper advance mechanism but also imposes control commands to theadvance mechanism. In this regard, one of the objects of my invention isto provide a single means for driving both the format control and thepaper moving or advance mechanism of a printer.

Another object of the invention is to provide a means for the abovepurpose which is fast acting so as to accomplish paper advance betweenprinting cycles in a minimum of time, thus, increasing the overall speedof the printer.

Another object of the invention is to provide a high energy, fast actingmechanical amplifier type mechanism for driving both the format controland paper moving mechanisms so as to maintain the total electrical powerrequired at a low level.

A still further object of the invention is to provide a system of thiskind wherein extremely low power electrical signals are employed torelease and utilize an abundance of mechanical energy.

A further object of the invention is to provide an improved springclutch mechanism for the above purpose, one of the improvements being inthe means for precisely aligning the input and output portions of thespring clutch.

Another object of the invention is to provide a paper advance mechanismwhich prevents cumulative error in the vertical spacing of the lines ofprint.

Another object of the invention is to provide a detented paper advancemechanism providing a zero reference feature such that any error in thevertical spacing in a single line of print is limited to that particularline of print. In

3,185,6'38 Patented May 25, 1%55 other words, the mechanism prevents theaddition of any error in a preceding line of print to succeeding linesof print.

Another object of the invention is to provide paper advance mechanismthat will automatically advance the paper one line unless it is desiredto skip one or more lines.

Another object of the invention is to provide a spring clutch mechanismhaving means for substantially eliminating backlash of the paper.

Another object of the invention is to provide a spring clutch mechanismto index the paper the same amount from line to line of print.

Another object of the invention is to provide a spring clutch mechanismadapted to drive all standard grades of paper and number of forms in thesame length of time.

Still another object of the invention is to prevent the paper frombacklashing more than a predetermined minimum amount so as tosubstantially maintain the paper in a single plane between the paperdrive mechanism and the print drum so as to eliminate problems incharacter registration.

Another object of the invention is to provide a system in which theformat control mechanism is driven by the spring clutch and controlsdisengagement of the clutch.

Another object of the invention is to provide a spring clutch mechanismhaving means to allow the output shaft of the spring clutch to coastonly during the last few degrees of its total motion, thus holding thetotal cycle time at a minimum.

A further object of the invention is to provide a spring clutchmechanism controlling the backlash of the output shaft of the clutch bymeans of a lug formed on the output shaft engaging a shoulder of aclutch actuating shell which is connected to the clutch input shaft bymeans of the drive spring.

Another object of the invention is to provide a spring clutch mechanismhaving an auti-backlash pin located such that the total backlash of theclutch output shaft will be maintained at a minimum, resulting in aneven lesser backlash on the paper tractor drive shaft.

Another object of the invention is to provide precise spring clutchmechanism in which the drive spring will disengage itself from theclutch input shaft only during the final few degrees of output shaftmotion.

Another object of the invention is to provide a spring clutch mechanismthat will insure precise operation over a long period of time and willoperate without servicing for seventy million or more cycles.

Another object of the invention is to provide a spring clutchconstruction of proper materials so as to insure negligible wear, thuspreventing the increase of backlash with use.

A still further object of the invention is to provide a spring clutchmechanism having a solenoid plunger and an anti-backlash pin, with theplunger and pin guide holes in the main support casting being positionedaccurately so as not to defeat the object of maintaining the backlash toa minimum.

These and other objects and advantages of the invention will becomeapparent by reference to the following specification and theaccompanying drawings, wherein:

FIGURE 1 is a schematic perspective view illustrating a portion of thedrive system of the printer disclosed in the referenced application, andparticularly illustrating the relationship of my paper advance mechanismand the format control device with the drive system of the printer.

FIGURE 2 is an exploded perspective view of the spring clutch which isschematically disclosed in FIGURE 1 and which drives both the paperadvancing assemblies of the printer and the format control device.

FIGURE 3 is a fragmentary vertical sectional view showing the details ofthe clutch mechanism of FIGURE 2 as they appear with the clutchassembled, and also showing both drive and driven belts connectedtherewith.

My invention is primarily concerned with the paper advance mechanism,certain details thereof, and with the relationship of the paper advancemechanism with a format control. The format control is not onlysynchronized with the paper advance mechanism, but also imposes controlcommands to the paper advance mechanism.

As mentioned before, a printer with which my invention can be used isfully described in application Serial No. 138,157. To the extentpertinent here, the printer uses a main drive motor 107 (FIGURE 1) fordriving substantially all of the movable parts of the printer, includingthe input shaft 117 of my spring clutch assembly 128. The driveconnection to shaft 117 is schematically shown as motor shaft 107a,pulley 127, belt 129, and pulley 130. Pulley 121 attached to shaft 107a,and belt 124 represent the main drive motor connection with other partsof the printer.

Spring clutch assembly 128 (described in detail later) has an outputshaft 118 to which pulleys 134 and 135 are secured. These have belts 140and 138 engaged therewith. Belt 138 mechanically drives a format controlor control device 375 through pulley 137, and belt 140 drives a papertractor drive mechanism 139. Thus the tractor drive mechanism 139 andthe format control 375 are synchronized.

For the purpose of my invention the format control 375 can be consideredconventional (the details are found in the referenced application),consisting of a photoelectric reader for coded tape 429 providingcommands or control signals over line 37 5b to clutch assembly 128 byway of OR gate 375d and line 3775a. The nature of the signals willdepend upon the codes in the tape, while their timing and frequency areslaved to the paper advance mechanism via clutch assembly 128.

Tractor drive mechanism 139 together with the paper tractors 384 (onlyone shown) are also conventional, e.g., the latter being a Kidder PressCompany, Model C-95 tractor. The illustrated tractor 384 includes asprocket driver actuated by shaft 382 (connected with drive 139) andsupported by a stationary guide shaft 383 and bracket. The paper 157 hassprocket holes engaged with the pins of the tractor.

The overall operation of the printer is such that it prints data oneline at a time on paper 157. However, the format control 375 issuesformat commands (electrical signals over line 3751: and/or line 375a)for the tractors 384 to move paper 157 through distances equal to thespaces required for one line, two lines, or more lines at a time betweenline print cycles. Paper drive spring clutch assembly 128 is largelyresponsible for the satisfactory operation of this portion of theprinter.

Assembly 128 includes a clutch, a solenoid actuating assembly 390(FIGURE 2) and an anti-backlash assembly 391. The spring clutch 128a(FIGURE 2) has the aforementioned input shaft 117 which is. drivencontinuously (by motor 107). Shaft 117 is mounted in a hearing 423(FIGURE 3) in one end of clutch housing 392 (FIGURE 3) which may beeither separately formed integral with support member 102 constituting apart of the frame of the printer. Housing 392 is provided with a cavity393 to receive the assembled spring clutch.

As seen in FIGURES 2 and 3 the inner end of input shaft 117 has a largerdiameter part 394 having a radial flange 395 extending from the outersurface thereof. Axial bore 396 (FIGURE 3) is formed in the part 394 andin the input shaft 117. An annular oilite or other suitable bearing 394ais fitted over part 394 and against flange 395 to provide bearingsurfaces for the shell or actuating sleeve 404 and the input end ahelical coil spring 403 of rectangular cross section. Spring 403 is apreloaded main drive spring as more fully described later.

Output shaft 118 of the spring clutch is also mounted in member 102 andit is in axial alignment with the input shaft 117. Shaft 118 (FIGURE 3)is mounted in a suitable bearing 397 disposed in a separate mountingmember 398 to provide access into the cavity 393. The previouslymentioned pulleys and 134 are secured to the end of the output shaft bysuitable conventional means.

The inner end of shaft 118 has an intermediate enlarged part 399, theleft end (as shown) of which is formed with ratchet teeth or lobes 400.The circumferential lengths of the lobes are substantially equivalent tothe space required for one line of print; while the other end of part399 is formed. to provide oppositely disposed, axially extending lugs401 extending over an intermediate reduced portion 402 of part 399(FIGURE 2). The extreme end of shaft 118 has a pilot 118a and a bearing405 to pilot in the axial bore 396. Portions 394 and 402 of the inputand output shafts have precise, identical diameters, and spring 403 isdisposed over these portions. The inner diameter of spring 403, whenfree, has an interference fit on portions 394 and 402 of the two shaftssuch that rotation of the input shaft 117 (when the spring 403 is free)causes the spring to wind tight on the two shafts in the manner of aself-energizing brake or clutch.

The clutch actuating shell or sleeve 404 is positioned over spring 403in a manner such that the radially-extending toe 403a of the spring isengaged in slot 406 in the end of sleeve 404. The axially-extending toe4014b at the opposite end of the spring engages the slot 408 formed inthe ring 409 which is secured to the portion 402 of shaft 118 by setscrews 410 (or the equivalent). Ring 409 serve as a bearing and a guidefor the lugs 411 extending from the actuating sleeve 404, which meshlike gear teeth with the corresponding lugs 401 extending from theoutput shaft 118. When the output shaft 118 and sleeve 404 are made ofmetal, ring 409 may be of a suitable bearing material; on the otherhand, ring 409 may be made of metal, such as steel, where the actuatingsleeve 404 is made of plastic such as nylon or Delrin. The actuatingsleeve 404 has ratchet teeth or lobes 412 formed on the outer surfacethereof, the lobes being in the same number as lobes 400 on shaft 118but extending in the opposite direction. The inner diameter of sleeve404 is larger than the outer diameter of spring 403 in its free positionso that the spring can be unwound to a larger diameter and therebyprevent its making mechanical connection between the input shaft and theoutput shaft and permit the input shaft to rotate free of the outputshaft.

Solenoid assembly 390 (FIGURE 2) consists of a conventional solenoid 414having an armature 414a which terminates in latch 413. The armature andlatch are spring-loaded by spring 4141) in a direction to engage thelatch with lobes 412 on the actuating sleeve. Thus, when the solenoid isnot energized, latch 413 is normally engaged with the ratchet teeth orlobes 412.

The anti-backlash device 391 is made of a latch 415 loaded by a properlymatched spring 416 in a direction so that the latch is always engagedagainst the lobes or ratchet teeth 400 on the output shaft 118.

Since the paper tractor drive 139 and the format control 375 are drivenby the same shaft (118) they are always synchronized and are subject tomotions of shaft 118 equally. This, of course, means that the benefitsof, for example, the anti-backlash feature, are distributed equally tothe paper tractor and to the format control.

From the foregoing it is understandable that the primary function of thepaper drive and format control is to start, continue and stop themovement of paper 157. The start signal can originate from any source,for example, from a computer, buffer, etc. over line 375c. The stopsignal can also be obtained from external sources and/or from the formatcontrol 375, the latter alternative being schematically shown inFIGURE 1. It is preferred, although not essential, that the start signalbe a high power signal and of short duration, for example that requiredto overdrive (electrically) solenoid 414 for a duration exactlycorresponding to that required for the spring clutch to drive the papertractor through a distance of one print line. Thus, when the high powersignal is received, it is impressed on solenoid 414 over line 375athrough OR gate 375d and over line 3752. No further signal is necessaryowing to the original hypothesis that the high power signal will be of aduration which is correct for the paper tractor to drive paper 157 onlyone line. In those cases where the format control 375 commands that thespring clutch 128 remain energized to drive the paper .157 two, three ormore lines, the electrical signal necessary for carrying out thiscommand is conducted on line 3751), through OR gate 375d and over line3752. However, the so called stop signal need not be a high power signalfor optimum response time characteristics (high acceleration), becausethe stop signal reaches solenoid 414 when it is already energized by thehigh power signal. In reality, the stop signal functions as a low powerholding signal which holds the solenoid energized (latch 413 of FIGURE 2retracted) for a time sufflcient to carry out the format controlcommand, i.e., whether one, two, three or more spaces corresponding tolines of print on the paper 157, are to be moved before the next printcycle.

Returning now to the operation of the mechanical phase of my springclutch 128, when solenoid latch 413 is separated from engagement withthe lobes 412 of sleeve M4, the clutch is prepared to drive as follows:sleeve 494 will begin to rotate due to toe 433a of the preloaded maindrive spring 4% pushing against it. In moving forward, spring 4% willgrip the continuously rotating input shaft 117. The input shaft will nowdrive the output shaft 118 through the main drive spring 403. After anadvance of paper corresponding to one line of print (owing to theduration of the high power signal on line 3750), solenoid 414 will havebeen de-energized and the latch 413 will be driven by spring 41415 intoengagement with the next lobe on sleeve 4%. However, the output shaft118 will continue to rotate in a forward direction due to inertia,thereby again unwinding or preloading the main drive spring 433, and thelugs 491 on output shaft 118 will immediately impact lugs 411 on theactuating sleeve, which is now being held at rest by latch 413. Latchpin 4-15 of the anti-backlash device is continuously urged into theanti-backlash lobes 490 of the output shaft by spring 416. Accordingly,when the output shaft 118 rebounds from the actuating sleeve 4%, it willimpact the pin 415 and be positioned by it.

Summarizing, paper 157 must move a distance corresponding to either oneline or a plurality of lines of print upon command. It has been foundthat the paper moves a single line at a time very accurately so that thedistance between any two printed lines is always within a closetolerance. This is accomplished by spacing the lobes of the springclutch at even intervals around the circum ference of the clutch.Further, the paper moves in a manner so as to prevent cumulative errorin vertical registration on printed line locations. This is due to thefact that the spring clutch will always bring itself back to itsoriginal starting point after one full cycle. No more than a very smallamount of paper backlash is allowed; thus, the paper will not buckle.This is assured by allowing only a negligible amount of spring clutchoutput shaft backlash, by the correct positioning of the anti-backlashpin.

It is understood that the illustrated embodiment of my invention isgiven by way of example only, and that all modifications, changes andthe like falling within the scope of the following claims may beresorted to.

What I claim as my invention is:

1. In a line printer having means for advancing paper through distancesequal to one or more print-line spaces depending upon the desiredformat; first means for advancing said paper; a driven means to providea signal for controlling the number of said spaces which said paper isto be advanced; and actuating means to simultaneously actuate said firstand said driven means, said actuating means operatively connected withand controlled by said driven means and including'a ratchet having onetooth for each space that the paper is advanced, and an electricallyoperated latch engageable with a tooth of said ratchet and actuated uponthe siganl from said driven means to automatically release one tooth ofsaid ratchet, and said latch being re-engageable with another tooth ofsaid ratchet to thereby enable said first means to advance the paperthrough a distance equal to one print-line space.

2. A spring clutch assembly comprising an input shaft having a flangeintermediate the ends thereof, an output shaft having a plurality ofdifferent diameter portions, an intermediate diameter portion beingidentical to the diameter of the adjacent end of said input shaft, aplurality of lobes formed on one end of the largest diameter portion ofsaid plurality of diameter portions, a first extension formed on theother end of said largest diameter portion of said plurality, a springsurrounding said identical diameter end and portions of said input andsaid output shafts respectively and abutting at its one end against saidflange of said input shaft, an actuating shell surrounding said spring,said shell having a central lobe section and a second extension on oneend thereof engaged with said first extension, and latch meansoperatively connected with said central lobe section.

3. In a line printer having means for advancing paper through distancesequal to one or more print-line spaces at a time depending upon theformat desired, first means for driving said paper; second means tocontrol the number of spaces that said paper should be driven, and thirdmeans driving said first and second means simultaneously, said thirdmeans being controlled by said second means and including an input shafthaving large and small diameter ends and a flange intermediate saidends, an output shaft having a plurality of different diameter portions,an intermediate diameter of said plurality of different diameterportions being identical to said large diameter end of said input shaft,a first lug formed on one end of said lar est diameter portion of saidplurality, a ring surrounding said intermediate diameter portion, aspring surrounding said identical end and portion of said input and saidoutput shafts respectively and abutting at its one end against saidflange of said input shaft and at its other end against said ring, asleeve'surrounding said spring, and said sleeve having a second lug onone end thereof engaging said first lug.

4. In a line printer having means for advancing paper through distancesequal to one or more print-line spaces at a time depending upon theformat desired, first means for driving said paper; second means tocontrol the number of spaces that said paper should be driven, and thirdmeans driving said first and second means simultaneously, said thirdmeans being controlled by said second means and including an input shafthaving large and small diameter ends and a flange intermediate saidends, an output shaft having a plurality of different diameter portions,an intermediate diameter portion of said plurality of dilferent diameterportions being identical to said large diameter end of said input shaft,a plurality of lobes formed on one end of the largest diameter portionof said plurality of portions, a first lug formed on the other end ofsaid largest diameter portion, a ring surrounding said intermediatediameter portion, a spring surrounding said identical end and portion ofsaid input and said output shafts respectively and abutting at its oneend against said flange of said input shaft and at its other end againstsaid ring, a sleeve surrounding said spring, said sleeve having acentral lobe section and a second lug on one end of said sleeve engagingsaid first lug, and latch means operatively engaging said central lobesection.

5. In a line printer having means for advancing paper through distancesequal to one or more print-line spaces at a time depending upon theformat desired, first means for driving said paper; second means tocontrol the numher of spaces that said paper should be driven, and thirdmeans driving said first and second means simultaneously, said thirdmeans controlled by said second means and including an input shafthaving large and small diameter ends and a flange intermediate saidends, an output shaft having a plurality of different diameter portions,an intermediate diameter portion of said plurality of different diameterportions being identical to said large diameter end of said input shaft,a plurality of ratchet teeth formed on one end of the largest diameterportion of said plurality of portions, a first lug formed on the otherend of said largest diameter portion of said plurality of portions, aring surrounding said intermediate diameter portion, a springsurrounding said identical diameter end and portion of said input andsaid output shafts respectively and abutting at its one end against saidflange of said input shaft and at its other end against said ring, asleeve surrounding said spring, said sleeve having a central ratchettoothed section and a second lug on one end of said sleeve and engagingsaid first lug, a first spring-loaded latch, normally engaging saidratchet toothed section, a solenoid to disengage said latch from saidtoothed section, and a second spring-loaded latch for engagement withsaid plurality of ratchet teeth.

6. A clutch mechanism comprising an input shaft adapted to be drivencontinuously, said shaft having large and small diameter ends and aflange intermediate said ends, an output shaft having a plurality ofdifferent diameter portions, an intermediate diameter portion of saidplurality of different diameter portions being identical to said largediameter end of said input shaft, a plurality of lobes formed on one endof the largest diameter portion of said plurality of diameter portions,a first lug formed on the other end of said largest diameter portion, aring surrounding said intermediate diameter portion, said ring having anotch on one end thereof, a spring surrounding said identical diameterend and portion of said input and said output shafts respectively andabutting at its one end against said flange of said input shaft and atits other end against said ring, said spring having bent ends thereon,one of said bent ends being in engagement with said notch. a sleevesurrounding said spring, said sleeve having a slot on one end thereoffor engagement with the other of said bent ends of said spring, saidsleeve having a central lobe section and a second lug on the other endthereof which meshes with said first lug, a solenoid having a firstspringloaded latch which engages said central lobe section when saidsolenoid is not energized, and an anti-backlash device including asecond latch and a spring biasing said latch into engagement with saidplurality of lobes.

7. A spring clutch mechanism comprising an input shaft adapted to bedriven continuously, an output shaft, said input and output shafts beingaligned and having adjacent cylindrical outer surfaces of identicaldiameter, said output shaft having a larger cylindrical portion theouter end of which is formed with a first set of ratchet teeth and theinner end of which is formed with axially extending lugs, a close woundcoil drive spring mounted over said adjacent cylindrical portions ofsaid input and said output shafts, and a sleeve mounted over said drivespring, the internal diameter of said sleeve providing sufiicientclearance to allow limited unwinding of said spring so as to preventsaid spring from gripping said shafts and providing a mechanicalconnection therebetween, said spring having a first toe formed at theinput shaft end iereof, said sleeve having a slot receiving said toe, asecond toe formed at the output shaft end of said spring, means couplingsaid second toe to said output shaft, the outer surface of said sleevehaving a second set of ratchet teeth, said second set of ratchet teethextending in the opposite direction from said first set of ratchet teethformed on said output shaft, and the output shaft end of said sleevebeing formed with axially extending lugs meshing with limited clearancewith said lugs formed on said output shaft.

8. An indexing, anti-backlash clutch mechanism, comprising a power inputshaft, the inner end of said input shaft having an outer cylindricalsurface and an axial bore, an output shaft having an outer cylindricalsurface and a pilot stem and sleeve bearing disposed in said axial boreof said input shaft, the diameters of said outer cylindrical surfaces ofsaid input and output shafts being identical, a close-wound helical coildrive spring positioned over said cylindrical surfaces of said input andsaid output shafts, said output shaft having an enlarged portion withthe outer end thereof formed with ratchet teeth and the adjacent innerend thereof formed with a pair of oppositely disposed lugs, a clutchshell comprising a cylindrical member positioned over said drive spring,said shell being formed with a pair of oppositely disposed lugs adaptedto mesh with the lugs on said output shaft, a slot on the end of saidshell opposite said lugs, a radially extending toe formed on the inputshaft end of said drive spring and engaging said slot, said drive springbeing formed at the output end thereof with a second toe, means couplingsaid second toe with said output shaft, the outer circumference of saidshell being formed intermediate the ends thereof with second ratchetteeth extending in a direction opposite to that of said ratchet teethformed on said output shaft, and anti-backlash means engaging saidsecond ratchet teeth.

9. A spring clutch mechanism comprising an input shaft adapted to bedriven continuously, an output shaft, said input and output shafts beingaligned and having adjacent cylindrical outer surfaces of identicaldiameter, said output shaft having a larger cylindrical portion theouter end of which is formed with a first set of ratchet teeth and theinner end of which is formed with axially extending lugs, a close woundcoil drive spring mounted over said adjacent cylindrical portions ofsaid input and said output shafts, a sleeve mounted over said drivespring, the internal diameter of said sleeve provides clearancesufficient to allow limited unwinding of said spring so as to preventsaid spring from gripping said shafts and providing a mechanicalconnection therebetween, said spring having a first toe formed at theinput shaft end thereof, and said sleeve having a slot engaged with saidfirst toe, said output shaft having a slot, and said spring having asecond toe formed at the output end thereof and received in the slot insaid output shaft, the outer surface of said sleeve being formed with asecond set of ratchet teeth, said second set of ratchet teeth extendingin the opposite direction from said first set of ratchet teeth formed onsaid output shaft, the output shaft end of said sleeve being formed withaxially extending lugs meshing with limited clearance with said lugsformed on said ouput shaft, a spring biased latch continuously urgedinto engagement with said ratchet teeth formed in said output shaft, asolenoid having a core member spring-biased to engage said ratchet teethformed on said sleeve when said solenoid is not energized and adapted tobe withdrawn from said ratchet teeth when said solenoid is energized,said spring clutch mechanism being constructed and arranged such thatenergizing said solenoid results in said main drive spring gripping bothsaid input and said output shafts so that said continuously rotatinginput shaft drives said output shaft and such that non-energizing saidsolenoid causes said core member to engage said second set of ratchetteeth on said sleeve and unwind said main drive spring to break themechanical connection between said input and output shafts, said meshinglugs being dimensioned so as to permit limited continued rotation ofsaid output shaft upon non-energization of said solenoid and theresulting stopping of said sleeve so as to preload said spring adetermined amount, and said spring biased latch engaging said ratchetteeth onsaid output shaft to maintain some preload of said spring.

10. In a printer for forming successive lines of print on a recordstrip, said printer having a support, first means for advancing saidrecord strip one or more lines at a mechanism for driving said first andsecond means simultaneously, said spring clutch mechanism being housedin said main support and comprising a continuously driven input shaft,an output shaft for driving said first and second means, said input andoutput shafts being piloted for purposes of alignment and havingabutting cyiindrical outer surfaces of identical diameter, said outputshaft having a larger cylindrical portion the outer end of which isformed with a first set of ratchet teeth and the inner end of which isformed with a pair of oppositely disposed lugs, a close Wound coil drivespring mounted over said abutting cylindrical portions of said input andsaid output shafts, a sleeve mounted over said springs, the internaldiameter of said sleeve being sufficient to allow limited unwinding ofsaid spring so as to prevent said spring from gripping said shafts andproviding a mechanical connection therebetween, said spring having afirst toe formed at the input shaft end thereof received in a slotformed in said sleeve and a second toe formed at the output end of saidspring, said output shaft having a slot rceiving said second toe, theouter surface of said sleeve being formed with a second set of ratchetteeth, said second set of ratchet teeth being the same in number as thenumber of teeth formed on said output shaft but extending in theopposite direction, the output shaft end of said sleeve being formedwith a pair of oppositely disposed lugs meshing with limited clearancewith said iugs formed on said output shaft, a floating spring-biasedlatch mounted in said main support and being continuously urged intosaid ratchet teeth formed in said output shaft, a solenoid having a coremember spring-biased to engage said ratchet teeth formed on said sleevewhen said solenoid is not energized and withdrawn from said ratchetteeth when said solenoid is energized, said spring clutch mechanismbeing constructed and arranged such that energizing said solenoidresults in said drive spring gripping both said input and said outputshafts so that said continuously rotating input shaft drives said outputshaft and such that de-energizing said solenoid causes said core memberto engage said second set of ratchet teeth on said sleeve and unwindsaid main drive spring to break the mechanical connection between saidinput and output shafts, said meshing lugs being dimensioned so as topermit limited continued rotation of said output shaft uponnon-energization of said solenoid and the resultant stopping of saidsleeve so as to preload said spring a predetermined amount, and saidfloating springbiased latch engaging said ratchet teeth on said outputshaft to maintain said spring preload.

11. An indexing, anti-backlash clutch mechanism, comprising an inputshaft adapted to be driven, the inner end of said input shaft having anouter cylindrical surface and an axial bore, an output shaft having anouter cylindrical surface and a pilot stem and sleeve bearing disposedin said axial bore of said input shaft, the diameters of said outercylindrical surfaces of said input and output shafts being identical, aclose-wound helical coil drive spring positioned over said cylindricalsurfaces of said input and said output shafts, said output shaft havingan enlarged portion with the outer end thereof having ratchet teeth andthe adjacent inner end thereof having a pair of oppositely disposedlugs, a clutch shell comprising a cylindrical member positioned oversaid drive spring, said shell being formed with a pair of oppositelydisposed lugs adapted to mesh with the lugs on said output shaft, a sloton the end of said shell opposite said lugs, a radially extending toeformed on the input shaft end of said drive spring and engaging saidslot, said drive spring being formed at the output end thereof with asecond toe, said output shaft having a slot with which said second toeis engaged, the outer circumference of said shell being formedintermediate the ends thereof with ratchet teeth, said ratchet teethbeing the same in number as said ratchet teeth formed on said outputshaft but extending in the opposite direction, a solenoid having aspring-biased plunger positioned so as to engage said ratchet teeth onsaid shell except when said solenoid is energized, and a separatespring-loaded plunger adapted to engage said ratchet teeth on saidoutput shaft so as to prevent backlash on said output shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,475,432 7/49Marihart 192-40 X 2,884,852 5/59 Saltz 197133 X 2,996,166 8/61 Bradshawet al. 197-130 3,018,721 1/62 Monticello et a1 10193 WILLIAM B. PENN,Primary Examiner. R. A. LEIGHEY, Examiner.

1. IN A LINE PRINTER HAVING MEANS FOR ADVANCING PAPER THROUGH DISTANCESEQUAL TO ONE OR MORE PRINT-LINE SPACES DEPENDING UPON THE DESIREDFORMAT; FIRST MEANS FOR ADVANCING SAID PAPER; A DRIVEN MEANS TO PROVIDEA SIGNAL FOR CONTROLLING THE NUMBER OF SAID SPACES WHICH SAID PAPER ISTO BE ADVANCED; AND ACTUATING MEANS TO SIMULTANEOUSLY ACTUATE SAID FIRSTAND SAID DRIVEN MEANS, SAID ACTUATING MEANS OPERATIVELY CONNECTED WITHAND CONTROLLED BY SAID DRIVEN MEANS AND INCLUDING A RATCHET HAVING ONETOOTH FOR EACH SPACE THAT THE PAPER IS ADVANCED, AND AN ELEC-